1. Field of the Invention
The present invention relates to a medical manipulator device that displaceably holds a medical instrument.
2. Description of the Related Art
Laparoscopic surgery using a laparoscope and fine thin forceps has been widely used in recent years. FIG. 12 is an explanatory drawing illustrating schematically the laparoscopic surgery using a laparoscope 102 and fine thin forceps 103. As shown in FIG. 12, in laparoscopic surgery, a surgical operation is performed by inserting the laparoscope 102 and fine thin forceps 103 into a body of a patient 101 from a small hole opened in the body of the patient 101. The laparoscope 102 is operated by a camera assistant 105, and the surgeon 106 performs the necessary procedure by using forceps 103, while observing an internal body image of the patient 101 picked up by the laparoscope 102 and projected on the monitor 104. Such laparoscopic surgery became very popular in recent years because its merits include a low physical and mental load on the patient 101.
In the laparoscopic surgery, in order to operate the forceps 103 with both hands, the surgeon 106 usually entrusts the camera assistant 105 with grasping and operating the laparoscope 102. Therefore, where communication between the surgeon 106 and camera assistant 105 is insufficient, a field of view that is optimum for the surgeon 106 cannot be obtained. Further, unstable hands of the camera assistant 105 sometimes destabilize the field of view.
Accordingly, a medical manipulator device such as an endoscopic robot that grasps and positions the laparoscope 102 has been suggested as a replacement for the cameral assistant 105.
For example, Japanese Patent Application Laid-open No. 9-276289 discloses features of a manipulator device that can grasp and position a laparoscope by a spherical joint and link mechanism.
However, with the feathers of the manipulator device disclosed in JP 9-276289 mentioned hereinabove, the entire device is large and the laparoscope is positioned by bending and stretching four links. Therefore, the region occupied by the device when the manipulator device is operated is large. The resultant inconvenience is that the mobility range of the surgeon in the surgery room is restricted.
Further, where an industrial actuator that is used in an industrial robot is to be used in a drive unit of such a medical manipulator device, problems are associated with cleanliness and reliability because the industrial actuators have not been developed for medical applications.
A typical endoscopic robot is equipped with a mechanism using an industrial actuator such as a stepping motor, and cleanliness is ensured, for example, by covering the entire robot with a sterilized drape or keeping the actuator away from the clean field. However, problems associated with reliability of medical manipulator devices using a stepping motor have been indicated. Thus, in a case where such a stepping motor fails during the surgery, it is necessary to interrupt the procedure for a long time in order to discard the robot and switch to the conventional method using no robot.
Further, in a case of industrial actuator with electric drive, failures such as current leakage or disconnection are a source of concern. Limitations are also placed on the cost reduction.